This invention relates to solar heat collectors and has particular reference to flat plate collectors adapted to be located in a position to intercept and absorb solar radiation and to transfer the resultant heat to a fluid circulating within suitable conduits associated with the collectors.
In some cases the conduits comprise water-conducting tubes which are formed in an aluminum panel by means of roll bonding. In other instances copper tubes of generally rectangular cross-sectional configuration are clamped to a copper sheet or plate.
It is highly desirable that copper tubing be used if possible since such tubing can be connected directly into a heating or water system, or the like, whereas collectors using aluminum, steel, or the like for the collector tubes require the use of an intermediate heat exchanger to isolate the collector from system impurities and corrosion.
Obviously, it is advantageous to employ copper tubing also because the requirement for accessory or corrective components or apparatus and complicated technical fabricating methods adds considerably to the overall cost of a solar heat collecting system. For example, the clamping of tubing to a collector plate requires additional structure. Brazing of copper tubing to copper plates requires large furnaces and high technology processing and may create undesirable stresses in the resultant panel.